Solar Cycle 25 Blog

On Dec. 31st, a wave of ionization swept through the high atmosphere over Europe when sunspot AR1389 unleashed another M2-class solar flare. "There was a very clear sudden ionospheric disturbance on my VLF radio instruments," reports Rob Stammes, who sends these data from the Polar Light Center in Lofoten, Norway:

"The sun is below the horizon where we are located north of the Arctic Circle," says Stammes. "This event shows we still have some contact with the sun."